NTSB Factual Report

HISTORY OF FLIGHT

On July 21, 2001, at 1322 central daylight time, a Beech K35, N6062E, was destroyed when it impacted the terrain three miles north of Grafton, Iowa. The private pilot and passenger sustained fatal injuries. The 14 CFR Part 91 personal flight departed Cherokee Municipal Airport (CKP), Cherokee, Iowa, approximately 1200, en route to the Wittman Regional Airport (OSH), Oshkosh, Wisconsin. Visual meteorological conditions prevailed along the planned route of flight, but witnesses reported thunderstorm conditions prevailed in the area at the time of the accident. No flight plan was filed and the pilot was not instrument rated.

A witness reported the pilot and his wife arrived at CKP on Friday, July 20, 2001. On Saturday morning the pilot refueled N6062E with about 43 gallons of 100LL aviation fuel. The witness reported the pilot was concerned about the weather and delayed the takeoff until about 1200. The witness reported the pilot checked the weather using the DTN weather service computer. The witness reported the pilot had him post a "For Sale" notice for N6062N in the CKP terminal. The pilot was flying to Oshkosh to attend the annual airshow.

A witness reported that at 1350 she saw airplane wreckage in a muddy bean field located about 1/2 mile east of Warbler Avenue and just north of 430th street, near Grafton, Iowa.

PERSONNEL INFORMATION

The pilot held a private pilot certificate with single engine and multi-engine land ratings. He held a Third Class Medical Certificate that was issued on March 14, 2001. He had a total of about 3,300 hours of flight time. A witness reported the pilot flew 50-60 hours in the accident airplane in the last 12 months. The pilot had flown the airplane about 12 hours since July 6, 2001. The pilot had purchased the airplane on March 29, 1996.

AIRCRAFT INFORMATION

The airplane was a single engine Beech K35, serial number D-5999. The airplane seated four and had a maximum gross weight of 2,950 pounds. The engine was a 260 horsepower Continental IO-470-C(9) engine. The last annual inspection was conducted on July 7, 2001. The airplane had flown about 12 hours since the annual inspection and had a total time of 3,972 hours.

METEOROLOGICAL CONDITIONS

The 1316 observed weather at the Austin Municipal Airport (AUM), Austin, Minnesota, located 17 miles northeast of the accident site was: wind from 250 degrees true at 23 knots gusting to 30 knots, visibility 5 miles in a thunderstorm with light rain, ceiling broken at 1,900 feet, second broken layer at 2,600 feet, overcast layer at 5,500 feet, temperature 26 degrees C, dew point 22 degrees C, altimeter 30.00. Remarks: automated weather observation system, lightning distant all quadrants.

The 1325 special weather observation at the Mason City Municipal Airport (MCW), Mason City, Iowa, located 19 miles southwest of the accident site, was: wind from 350 degrees at 7 knots, visibility 4 miles with a thunderstorm in the vicinity and haze, a few clouds at 2,000 feet, scattered clouds at 3,400 feet, ceiling broken at 4,800 feet, temperature 28 degrees C, dew point 25 degrees C, altimeter 29.97. Remarks: automated observation system, lightning distant north and northeast, thunderstorm began at 1319.

The 1258 special weather observation at the Albert Lea Municipal Airport (AEL), Albert Lee, Minnesota, located 20 miles northwest of the accident site, was: wind from 260 degrees at 8 knots gusting to 18 knots, visibility 3/4 miles, ceiling overcast at 200 feet, temperature 20 degrees C, dew point 18 degrees C, altimeter 30.02. Remarks: automated observation system, lightning distant all quadrants.

The 1319 special weather observation at AEL was: wind from 070 degrees at 7 knots, visibility 7 miles, scattered clouds at 400 feet, scattered clouds at 1,700 feet, ceiling overcast at 2,300 feet, temperature 20 degrees C, dew point 18 degrees C, altimeter 29.98. Remarks: automated weather observation system, lightning distant all quadrants.

An aviation Area Forecast (FA) was issued at 1048 on July 21, 2001, and was valid until 1700. The forecast for northwest Iowa, was: scattered clouds at 3,000 feet agl, ceiling broken at 10,000 feet with tops to 25,000 feet, with widely scattered thunderstorms and moderate rain, with thunderstorms occasionally in clusters and possibly severe. Cumulonimbus cloud tops to 45,000 feet.

The National Transportation Safety Board (NTSB) Meteorology Factual report stated that at 1319:58, a weather surveillance radar depicted two main areas of echoes over northern and central Iowa and southeast Minnesota, with the most organized and intense echo directly over the accident site. The NTSB report stated the following:

"The general route of flight indicates an area approximately 100 miles of light to moderate intensity echoes over Iowa with a few embedded areas of strong echoes, an approximately 20 mile break occurs before the activity rapidly intensifies in the vicinity of the accident site. Activity over the accident site indicates an organized area of intense to extreme echoes with reflectivities of 50 dBZ and greater, extending from 5 miles south to 20 miles north of the accident site. The area north then becomes less organized, but continuing for another 80 miles north and northwest with a few embedded areas of strong to intense echoes. The general route of flight indicates the flight was operating under light to moderate weather echoes for the majority of the flight, a brief break in the echoes until just prior to encountering intense to extreme echoes in the general vicinity of the accident site."

One witness, a Deputy Sheriff for Worth County, Iowa, reported that at approximately 1258 he noticed a thunderstorm to the west-northwest approaching the area near Grafton, Iowa, and he drove to the northwest part of town to monitor the weather conditions. The deputy indicated that the approaching thunderstorm was dark looking and he observed lightning and the gust front as he approached the area northwest of town. By the time he arrived on the northwest side of town at approximately 1318, he radioed into dispatch his position and intention on monitoring the storm, when he encountered frequent lightning, heavy rain, high winds gusts estimated in excess of 50 miles per hour, and intermittent pea size hail. The heavy rain severely limited visibility even with his windshield wipers on and reported numerous close cloud-to-ground lightning strikes. The main part of the storm ended at approximately 1328 at his location and moved east-southeast. At approximately 1405, he was notified by dispatch of an aircraft accident approximately 2 miles from the position where he reported the weather conditions. He responded to the accident scene and was the first law officer at the site.

Another witness was located approximately one mile north of the accident site. The witness indicated that he had been working in a shed between approximately 1315 and 1330, when the thunderstorm moved across the area with a heavy downpour of rain, high winds, pea size hail, and lightning. Immediately after the storm he had checked the rain gauge, which measured 1.00 inch of rain during the brief 15-minute period. (See Meteorology Factual Report)

WRECKAGE AND IMPACT INFORMATION

The airplane wreckage impacted the terrain in a soybean field at coordinates N 43 degrees 23.169 minutes, W 093 degrees 3.240 minutes, on a heading of 241 degrees magnetic. Green glass pieces were found at the initial point of impact. A furrow 28 feet long proceeded from the initial impact point to where a hole measuring 5 feet across and 4 feet deep was found. The engine was lying next to the hole. Both magnetos were lying on top of the engine, but had broken from their mounts and the magneto drive gears were missing from the engine. The engine firewall and parts of the instrument panel, control column, and radios were crushed onto the rear of the engine. No instrument or avionics readings were obtained. The propeller flange was found broken off the crankshaft.

The main body of the wreckage traveled for approximately 108 feet from the engine. The main body of the wreckage consisted of the empennage with its ruddervators, the top of the fuselage from the empennage section, and the wing carry-through section. The ruddervators had separated by from the tailcone but were still attached by the trim cables. The fuselage and cabin were destroyed. The upper portion of the fuselage remained attached to the empennage along the upper skin. The lower portion was fragmented and found in the same vicinity.

The left wing was found forty feet to the northwest of the main body of the wreckage. The wingtip was intact. The leading edge of the wing showed no signs of impact damage. The trailing edge of the wing was crushed with the aileron and half of the flap being pushed into the rear spar. The wing had separated from the fuselage at the just outboard of the wing attach points.

The right wing was found twenty-five feet to the southeast of the main body of the wreckage. The wing exhibited angular aft crushing of the leading edge. The wingtip was torn from the wing, as were the aileron and flap. The flap was found bent double at the inboard end. The outboard end of the flap had separated, and exhibited torn edges and aft and downward crushing. The aileron exhibited crushing and was bent in a bowed condition.

All primary and secondary flight controls were located at the accident site. Flight control cable continuity was confirmed at the accident site. All cable ends were accounted for, as were their connections to flight control surfaces and actuation mechanisms. One aileron cable was found separated and both ends of the break had signatures consistent with tensile overload. This aileron cable was found attached to the control column at one end and to its bell crank horn at the other.

The engine inspection revealed the engine could not be rotated. The crankshaft was separated inside the crankcase halves. The number 4, 5, and 6 pushrods and cylinder 5 and 6 had impact damage. The magnetos could not be rotated. The magnetos were opened and mud and water were found in the interiors, but no internal damage was noted. Fuel was found in the fuel manifold.

The propeller had separated from the engine just forward of the thrust flange. One blade separated from the hub and was folded toward the non-cambered side about 100 degrees. It exhibited knicks and gouges along the leading and trailing edges and chordwise scratching. The other blade remained attached to the hub and was straight except for a twist. A gouge was noted on the leading edge near the blade tip.

The inspection of the attitude indicator found rotational scoring on the gyro and gyro housing.

MEDICAL AND PATHOLOGICAL INFORMATION

Autopsies were performed on the pilot and the passenger at the Mercy Medical Center in Mason City, Iowa, on July 22, 2001.

A Forensic Toxicology Fatal Accident Report was prepared on the pilot by the FAA Civil Aeromedical Institute. The results were negative except for postmortem ethanol formation.

ADDITIONAL INFORMATION

Parties to the investigation included the FAA, Raytheon Aircraft Company, and Continental Motors.

The airplane wreckage was released to Mr. Jackson Wells on July 26, 2001.

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NTSB Probable Cause

The pilot's improper inflight decision to continue into known adverse weather. A factor was the thunderstorm.